Process of ore concentration.



W. A. SCOTT.

PROCESS OF ORE CONCENTRATION.

APRLICATION EILED DEC.15, I916.

l wfifimo I Patented Aug. 2?, 1918.

EYE AT PATENT idlFllQ.

WALTER A. SCOTT, OF CHICAGO, ILLINOIS, ASSIGNOR T0 MINERALS SEPARATION NORTH AMERICAN CORPORATION, A CORPORATION OF MARYLAND.

PROCESS OF ORE CONCENTRATION.

Application filed December 15, 1916.

To all whom it may concern:

Be it known that I, WALTER A. ScoTT, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Process of Ore Concentration, of which the following is a specification.

My invention relates to the process of ore concentration commonly known as the flotation process. As is well known, this process, generally speaking, consists in adding to a freely flowing ore pulp some suitable frothing agent, and thereafter introducing into or generating in the mixture a gas, the efiect of the operation being to cause the metalliferous or other valuable part of the minerals, such as graphite, to float as a froth consisting of air bubbles partially or wholly covered with the mineral particles. The frothing agents used for this purpose comprise a wide variety of substances, such as oils, fatty matters, coal tar, wood tar, derivatives of coal and wood tar, and many other substances.

When the gas is introduced into the mixture, as distinguished from being generated in the mixture, such introduction of gas is effected in a variety of ways, as by agitating the pulp mixture in such a manner as to introduce atmospheric air, and by introducing the gas-generally air-into the mixture through a permeable medium forming part of the containing vessel, or forming part of an air cell submerged in the pulp.

However the process is practised, it is necessary that the frothing agent be thoroughly disseminated through the mixture. When the frothing agent is soluble, or contains soluble ingredients, the dissemination of the soluble matter is efiected with comparative case, but an insoluble frothing agent, or the insoluble ingredients thereof, can be disseminated homogeneously through the mixture only by the expenditure of consider able energy in the form of mechanical agitati'on.

According to my invention, I disseminate the frothing agent in a comparatively small volume of water before adding it to the ore pulp. By means of this procedure a large saving of energy is effected. By first making a homogeneous mixture of the finely di vided frothing agent in a small amount of water, it is simply necessary that the requi- Specification of Letters Patent.

Patented Aug. 2'2, 1918.

Serial No. 137,115.

site amount of this homogeneous mixture be added to the ore pulp, whereupon simple stirring, or merely the flow of a pulp through the launders in which it is conveyed, sufiices to distribute the frothing agent throughout the large body of ore pulp.

The particular manner in which according to my invention I effect the preliminary mixing or diffusion of the frothing agent with water is that commonly known in connection with the treatment of milk as homogenizing. This process of homogenizing as applied to milk consists in forcing the milk by high pressure through minute orifices. The effect of such procedure is to divide the globules of fat into much smaller particles than occur in natural milk, thus eflecting a more intimate distribution ofthe butter-fat throughout the milk. As applied to milk this process has the effect of preventing the accidental churning of the milk into butter during transportation and incidentally has the efi'ectnot desirable in the case of milkof precluding the possibility of whipping cream that has been homogenized. Homogenizing also to a considerable extent, if not completely, prevents the separation of cream from milk.

These various effects upon milk and cream growing out of the homogenizing process are all believed to be due to the finer sub division of the fat in the homogenized prodnot than in the natural product. Similarly, the application of the homogenizing process to a mixture of an insoluble oil, or other frothing agent containing an insoluble ingredient, in water has the effect of subdividing the frothing agent to an extent that cannot be obtained by simple mechanical agitation, and the desired efiect is also obtained with the expenditure of an amount of energy quite insignificant compared with that used in agitating a mixture of ore pulp with frothing agent. The proportion of frothing agent to water in the mixture to -be homogenized according to my process is not restricted, but may be varied within wide limits, but one of the advantages of the proc ess is that the frothing agent can be homogenized in an amount of water very small compared to the entire body of ore pulp to which the mixture is afterward added, thus effecting a saving of energy, growing out of the manipulation of a small body of water,

as compared to the necessity of agitating the entire ore pulp for the purpose of disseminating the oil therein.

After the homogeneous mixture of oil and water is prepared, the mixture is added to the ore pulp, whereupon the homogenized product diffuses almost immediately through the entire ore pulp without the expenditure of further energy. Furthermore, by reason of the exceedingly minute subdivision of the frothing agent efiected by the homogenizing process, the frothing agent is more active than when applied according to methods now in vogue, thus efiecting an economy of frothing agent, and leading to superior re sults.

In the drawings T have illustrated one form of apparatus suitable for homogenizing the insoluble frothing agent or the insoluble ingredient thereof with water, but my invention is not restricted to the use of this or any other particular form of apparatus for the process. Tn fact the apparatus illustrated is old and in common use for the purpose of homogenizing mill: and is illustrated and described in detail in Patent No. 1,14t5,600 granted to M. Leitch and Wright July 6, 1915.

In the drawings,

Figure 1 is a view in elevation, partially in section, of the homogenizing apparatus, the part in section being upon the plane indicated by the line l1 of Fig. 3.

Fig. 2 is a similar view, the part in section being along the plane indicated by the line 22 of Fig. 3, and

Fig. 3 is a section viewed from below on a plane between two of the blades of which the homogenizing element proper is built up.

A indicates a shaft which may be support ed and revolved in any approved manner. This shaft carries a bottom plate Z2 having an annular depression or distributing chamher 0. The upper portion of the shaft is bored out to form a central receiving chamber d for the materials to be emulsified; and, leading from this central receiving chamber are a number of passages e, tangent to the wall of the chamber, these passages serving -to supply the material from the central chamber to the emulsifying elements of the device.

Surrounding the outer wall of the receiving chamber 66 are a plurality of plates f, each having upon its upper face an annular groove 0 corresponding to the annular depressions or distributing chambers c of the bottom plate 6, and having in its lower side a number of slots or grooves g which form continuations of the tangential passages e in the wall of the central chamber.

The slots or grooves g, in the lower face of each of the plates f serve as feeding passages respectively to the annular depressions or distributing chambers 0 in the upper face of the several proximate elements. A key in engaging in corresponding key-ways in the shaft and in the several elements to be assembled causes the slots 9 to register accurately with the tangential passages e in the wall of the central chamber.

The top plate 71 rests upon the uppermost plate 7 of the series of emulsifying elements and has in its under-face slots corresponding to those in the under-faces of the several plates f. A nut j engaging a thread on the upper end of the shaft, when screwed down against the plate 2', holds the assembled elements together.

Tn each of the plates f, and in the top plate 2' are a-number of vertical grooves 70, spaced at suitable distances apart about the outer periphery of the wall of the central chamber. These vertical grooves communicate with an annular groove around the shaft at Z and serve as air vents from the several sections to the said annular groo-veZ and thence from the annular groove Z through corresponding vertical grooves m in the nut Tn cross section, the slots or grooves 9 preferably deepen from without inwardly; and the annular depressions or distributing chambers c deepen from within outwardly. This arrangement is found to facilitate regularity and uniformity of feed and dis charge of the materials to be emulsified.

The operation of the device is as follows: The material to be emulsified, which is preferably first roughly mixed, is fed into the central chamber (Z in any approved manner. Tt is immediately thrown out against the wall of the chamber and discharged through the passages e. The tangential arrangement of these passages facilitates the entrance of the liquid and its feed into the slots or grooves 9. These slots or grooves 9 feed the material into the annular surface depres sions or distributing chambers c, where, because of the high speed of rotation of the device a centrifugal force is set up. The outer wall a of the annular surface groove 0 in each element is slightly lower than the central portion of the element, thereby leaving a very narrow orifice between the top of the wall a and the bottom of the element above,-this intervening space, in many instances, being as small as one-thousandth of an inch in height. The pressure caused by the centrifugal force, acting upon the material in the depressions or distributing chambers c, forces the material through the very narrow discharge orifices, and mixes the particles so thoroughly as to form the desired emulsion. During the operation, any air that is entrained with the material and which would otherwise tend to interfere with the proper feed thereof is carried off by the venting grooves.

-#lnother suitable form of apparatus for homogenizin the mixture is shown in the patent to W illmann No. 1,070,218 granted August 12, 1913.

It will be understood that I make no claim to any novelty in the form of apparatus used, my invention being confined to the concentration process described herein, in which suitable homogenizing apparatus of any form is used.

What I claim is:

l. A concentration process comprising the operations of forming an unaerated emulsion of an insoluble trot-hing agent in a comparatively small amount of Water, the addition of a suitable amount of the emulsion to an ore pulp, and the flotation of the valuable product contained in the pulp.

2. The process of ore concentration comprising the operations of forming an unaerated emulsion of an insoluble frothing agent in a comparatively small amount of water, the addition of a suitable amount of the emulsion to an ore pulp, and the introduction into the ore pulp of a gas for the purpose of efi'ecting flotation.

3. The process oi concentrating ores com prising the operations of forcing a mixture of an insoluble frothing agent and Water through fine orifices, the addition of a suitable amount of the product so formed to an ore Pulp, and the flotation of the metallifer ous matter contained in the ore pulp.

In testimony whereof I have subscribed my name.

WALTER A. SCOTT. 

